David
I solved that problem in my bird song trap for the last twelve
years by feeding the output of my mic preamp into an equalizer. I
originally used one scavenged from an old hi-fi system but eventually
bought a mono ten band equalizer, the AudioSource EQ10.1 - -Ten Band
Equalizer, at Crutchfield I believe about 8 years ago. It worked well
for this purpose.
I usually cut off the 30,50,125 and 250 Hz bands and boosted the 4,8,
and 16Khz bands. I am mainly interested in warblers.
Greg Kunkel
--- David Martin <> wrote:
> Thanks to everyone for the suggestions on the high-pass filter.
>
> I think I need to explain my problem better. I put the mic on my
> roof to detect the flight calls made by migrating birds,. The
> calls
> are characteristically short and high pitched. I want to set the
> gain on my system as high as possible so I can get the maximum
> sensitivity and record calls that are weaker and/or made by more
> distant birds. The large amount of low frequency noise in my area
> increases the total sound level so high that clipping is sometimes
> a
> problem when I set the gain high. The calls I'm interested in are
> all > 2000 Hz, so by filtering the input I could get rid of a lot
> the
> noise (without affecting the bird calls) and therefore be able to
> push the gain higher. For this project I'm not looking for a nice
> "natural sound" -- just interpretable data.
>
> I monitor the skies from sunset to sunrise (9-10 h) so the sound
> files I collect are huge (>1GB) . I use specialized software
> (www.oldbird.org) to extract the flight calls of the birds. That
>
> step seems to work ok even with the noisy recordings.
>
> The Shure filter Dan suggested will provide some help and I'm going
>
> to get one to try in the short run. But, in the long run I think I
>
> will try to build a filter. The site Phil pointed out seems like a
> good start.
>
> David
>
>
> At 11:22 PM 8/15/2007, you wrote:
> >Hello David,
> >
> >I think that you can use the sound program Audacity to filter
> sound files.
> >Look at the FFT filter under effects menu.
> >
> >Everett
> >
> >
> >
> >At 06:28 PM 8/14/2007, David Martin wrote:
> >
> > >I've had it working for three nights now. I'm getting decent
> > >signals, but I'd like to use as much gain as possible. However,
> low
> > >frequency noise from traffic, trains, and and aircraft can
> overload
> > >the system. (I'm a mile from relatively busy railroad tracks and
> 10
> > >miles from a busy airport). I am just monitoring songbird
> flight
> > >calls and only need to record above 2000 Hz, so I should be able
> to
> > >greatly reduce the problem with a high-pass filter. Can anyone
> > >suggest a filter that might work or does anyone know of a plan
> for
> > >building one?
> > >
> > >David
> > >
> > >
> > >
> > >
> > >"While a picture is worth a thousand words, a
> > >sound is worth a thousand pictures." R. Murray Schafer via
> Bernie Krause
> > >
> > >Yahoo! Groups Links
> > >
> > >
> > >
> >
> >
> >
> >
> >"While a picture is worth a thousand words, a
> >sound is worth a thousand pictures." R. Murray Schafer via Bernie
> Krause
> >
> >Yahoo! Groups Links
> >
> >
> >
>
>
>
>
> "While a picture is worth a thousand words, a
> sound is worth a thousand pictures." R. Murray Schafer via Bernie
> Krause
>
> Yahoo! Groups Links
>
>
>
>
Sick sense of humor? Visit Yahoo! TV's
Comedy with an Edge to see what's on, when.
http://tv.yahoo.com/collections/222
"While a picture is worth a thousand words, a
sound is worth a thousand pictures." R. Murray Schafer via Bernie Krause
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